Trenching machine



Jan. 19, 1954 G. w. MOININCH 2,666,273

TRENCHING MACHINE Filed April 4, 1950 2 Sheets Sheet l G13 7 HQIALY cK .Jan. 19, 1954 G. w. MommcH 2,666,273

TRENCHING MACHINE Filed April 4. 1950 2 Sheets-Sheet 2 Patente a 19, 1954 TRENCI-IING MACHINE V Glenn W. McIuinch, Omaha, Nebn, assignor to Auburn Machine Works, Inc., Auburn, Nebr., a

corporation of Nebraska Application April 4, 1950, Serial No. 153,967

The present invention pertains to improvements in trench-digging machines and more particularly to digger bits and holders therefor.

It is an object'of the present invention to provide a novel digger-bit and mounting therefor of durable and strong construction, particularly suitable for lightweight, low: cost trench-digging machines. It isanoth'er object of the present invention to provide a digger-bit construction which is capableof efficiently digging and elevatlng loosened soil from a trench even under the most adverse operating conditions.

A further object of the present invention is to provide a digger-bit and mounting construction which includes novel'structure for causing the bits to operate'efficiently under varying soil conditions vention to provide a digger-bit and mounting which are readily adapted to dig trenches of vari ous widths. Y I w it is a more detailed object of thep'resent invention to provide a digger-bit construction which insures against" loss of the bit in operation and precisely retains the bit in -the desired oper ating position. I I

Other objects and aims of the present invention will become 'apparentas the following'de-j 'scription of a preferred embodiment of my 1115 vention proceeds, in which:

[Figure 1 is a bottom face view'ofa portion of an endless link chain with diggerbits and holders embodying thepresent invention assembled in normal operating position.

Fig. 2 is a side elevation of the assembly shown in Fig. 1 lowered intooperatil g position relative to the-forward wallof" a trench.

Fig. 3 is aperspective of a single digger-bit.

Fig. 4 is an end:views ofa straight portion of endless chain with-the digger-bits in normal position; a

i -:Fig; 5is a sideelevation partially;incross-section taken along the line 55. of Fig.4, I, r Y Fig.6 is a transverse cross-section of one of the digger-bit holders taken alongthe line 6-6 ofFig.5..

Fig. 7 is adiagrammatic' view of the relative position of the digger-bitsarranged for digging loose, sandy soil, 4 Q fv "Fig. dis a diagrammatic view of therelative position of thedigger-bits arranged for digging .hard; stony soil'or'clay. 9

' While the inv ention' is susceptible of various modifications and alternative constructions, I have shown in the drawings and willjdescribe in detail the preferred embodiment, but it is ts be 2 Claims. (Cl. 37-191) It is also an object of the present in-' understood that I do not thereby intend to limit the invention to the specific form disclosed, but intend to cover all modifications and alternative constructions and uses falling within the spirit and scope of the invention as expressed in theappended claims.

Referring more particularly to the drawings, Figs. 1 and 2 show an endless chain l l! with digger-bits II and holders l2 mounted thereon.

The endless chain isof the common roller link type, having a series of transverse rollers I4 held in parallel spaced relationshi by pairs of inside links 1-5 and overlapping outside links Hi. Pins or rivets l8 passing through holes in the end portion of links I 5, l6 and axial bores in the rollers I4 securely hold the parts of the chain in position.

Trenching machines adapted for using the endless chain type of digger are well known and a detailed description of their construction is not necessary to an understanding of the present invention. An exemplary device is disclosed in the copending Schmidt application, Serial No. 755,825, assigned to a commonassignee. it to say that the chain [0 is trained in an endless loop over a pair of spaced sprocket wheels I9 mounted on opposite ends of a beam 20. The beam is pivotally connected for vertical swing at one of its ends to a trencher frame which is supported for movement along the surface of the ground in the direction the desired trench is to be dug. As shown in Fig. 2, the digger-bits I! are mounted at uniformly spaced points on the loop of chain and project outwardly therefrom. A"

suitable source of power, such as a gasoline engine, drives the sprocket located adjacent the pivotal connection to the frame causing the chain to movethe bits upwardly against theearth.

Preferably the forward movement of the trencher frame is coordinated with the speed of the chain to move the bits into the forward wall of the trench at a uniform rate causing each bit to take the same'size bite of earth. Lateral conveyors adjacent the upper end of the frame' will be explained presently. The blade portion 22 of the bit has a transverse forward cutting edge 23 of suitable length for the size and type of trenching machine with which the bit is to be used. I have found that a two inch blade is highly satisfactory for a lightweight machine such as that disclosed in the above copending application. As shown in the drawing, the blade of the bit has a chisel shape which is formed by a rearwardly extending triangular upper face 24 and a beveled lower face 25 extending downwardly and rearwardly from the cutting edge to a line of intersection with the opposite side of the shank. A slope of about 20 for the lower face 23 provides an efiicien't cutting edge. The lateral edges 26, 21 of the blade are necked in wardly providing side draft or relief for the bottom face 25 which commonly constitutes the working or leading face of the bit.

The bits I I are positively and rigidly supported on the chain by the holders l2 which are adapted for rapid, simple interchange and multi' ple positioning of the bits II and holders 62.

The holders have a body portion or saddle 29 which overlies the chain, and a pair of mounting l'g's' 30'which project downwardly from the saddle 29 along the sides of the chain. The legs 30' are spaced apart a distance equal to the spacing between a pair of outside links I6 so that a pair of outside chain links may be readily replaced by the leg's 30 of the holders. The holders are connected to the chain and held in straddling position by transverse pins or connectors passing through holes in the legsspaced to correspond to the holes in the pairs of outside links [6 replaced by the holders. To provide for ready installation and removal of any holder, bolts 3i and nuts 32 are provided for this purpose. To prevent accidental loosening" of the connectors; the nuts 32 are of the castle type and are fitted with cotter pins 33. If desired, the bolts 31 may be restrained from'turning relative to the holdersl2 by using bolts having a square or T-shaped head- 34 engaged by a laterally extending rib 35' or the like on the outside of each leg 30.

Additional supportfor the digger bit holders i2 is provided by rearwardly extending lugs or projections 36 formed integrally with the upper edge portion of the legs 30 of the holder. The lugs 36 project rearwardly to or slightly beyond the axis of the next adjacent roller M of the chain and have their bottom edges curved upwardly to conform to the contour of the following outside links [5. It will be apparent by ref erence to Fig. that the lugs 36' resist rearward tipping forces on the holder and provide a third point of support greatly increasing the strength and evenness of operation of the digger chain.

Mounted on the saddle 29 of the holder I2 is a clamp or vise, indicated generally at 31, for securely gripping and retaining the shank 2! of the digger bits I I. The clamp comprises a mas: s'ive', columndike support of generally 'rectangu lar outline extending fore and aft for the length of the holder l2. The outer portion of the clamp is provided with a pair of opposed gripping jaws 38 forming a split sleeve with a longitudinal hole or bore 39 corresponding in cross-sectional con= tour and Site with that or the Shank 2| 0f the bit; The bore 39 is abruptly or sharply reduced in size at its trailing end portion to form a collar or abutment 40 which acts as a positive stop limit ing the rearward movement of the bit in the holder. The jaws 38 of the clamp are drawn toward each other for applying gripping pressure to the sides of the shank 2| oi the bit merely by tightening a bolt 4| and nut 42 which are inserted in a transverse hole 43 drilled through the jaws of the clamp. A cotter pin 44 and castle nut 42 may be provided to prevent accidental loosening of the jaws 38 of the clamp.

A suitable angle of attack for the working face and edge of the bit II, as well as for allowing clearance fdr the; holders I2, is provided by sloping the bore 39' of the clamp outwardly from back to front from the saddle 29 of the holder. In the preferred embodiment an outward angle of about 20 from the saddle provides adequate clearance arid presents the cutting edge of the bit at an angle for effective removal of dirt from the forwere edgeof the trench. The angle used in any particular construction will depend on the length of the bit, the amount of bevel on the working face, and the slope of the frame supporting the endless chain.

For digging a trench of greater width than that of anindividual digger-bit; the holders l2 are adapted to provide increasing; lateral offset of the bits H; To accomplish this, the holders are mounted on the chain in a series beginning with a center holder l 2a; and followed by pairs of alternate right and; left hand enlarging holders [2b, L20; i211. Such a series of holders is repeated throughout the length ofthe loop of digger chain to provide continuous digging of atrench having a width equal tothe span or the digger-bits H in the widest pair of enlarging holders. v

The digger-bits an; relatively offset by varying the sidewise angular and bodilydisplacement of the clamping portions of the holders. The clamping portion ofthe center holder IZa is located directly over the saddle 2-9 and is aligned witht-he centerlineof the chain so that a bit mounted in this holder will remove the dirt from the middle of the trench width. The clamps of the first pair of enlarging holders l2b are located; over the saddle portions and are alternately angled laterally of the direction of movement of the chain; The amount of lateral angularity should be suiiicient to give a substantial increase in trench width over the bit in the center holder I29; but should also allow some overlapbetween the paths of the center bit and the following pair of bits. I have found. that a horizontal angle of about 15 degrees between the center lineofth chain aha the axis of the bore 39 is satisfactory fora bithaving a two inch leading edge. The angi-ilar offset of the enlarging holders not only provides increased span but also positions the digger-bits relative to the cutting wall for more efficient removal ofthe dirt.

Greater lateral offset is provided by transverse bodily displacement of the clamping portions of the holders relative to the chain in addition to the angular offset described for the first pair of enlarging bits. Thus the second pair of enlarg ing holders- I26 have the clamping portions located approiiimately stave ppd'sit sides of the homer, while the than pair of" holders 12a has an opposed outward lateral extension 45 on the saddle to support the clamping portion. 1? have rquha that an bvenapf or about one-quarter of the width of the cutting edge is suitame for a two-inch blade so that the width of succeeding cuts will be approximately 2, 5, 8 and 11 inches. It will be appreciated, however, that the amount of overlap will depend on the particular dimensions and construction of the digger-bits and ers d; ,c

Highly emcien-t digging action for various types tion.

of soils and soil conditions is obtained with dig erbits and holders constructed in accordance with the present invention. As shown in Fig. 4, the digger-bits II ar mounted in the holders I 2 for normal digging operation of ordinary packed earth or loam. In this position the cutting edge 23 of the bit is substantially parallel to the transverse plane of the endless chain I0. Positive interference between the flat sides of the polygonal cross-sections of the shank 2| of the bit, and the bore 39 of the holder holds the bitsin the desired angular position. i It will be apparent, however, that the bit may be inserted in the holder with the blade 22 inclined at various angles with respect to the normal position by orienting the bit through the angle required to bring succeeding sides of the shank into parallel with the sides of the bore 39 of the holder.

A precise locking action retaining the bits in the various angular positions and restraining the bits against accidental longitudinal displacement and loss is provided by engagement between the sides of a transverse locking groove 41 formed in the shank of the bit and the tightening bolt 4| The bolt receiving hole 43 is positioned on the jaws 38 of the holder to intersect chordwise the surface of the bore 39, thereby causing the bolt 4| to lie at least partially within the path of movement of the shank of the bit. The groove 4'! lies across one edge of the shank so that it mates with the receiving hole 43 when the bit is fully inserted into the holder and bears against the abutment or stop 40. To permit locking of th bit in auxiliary angular positions, additional locking grooves 48 intersecting adjacent edges of th shank are provided. In a given orientation of the bit, the tightening bolt 4| will engage, at least, one of these locking grooves 41, 48. Thus when the tightening bolt 4| is inserted into the clamp after the bit has been properly positioned, the shank of the bit is securely restrained against longitudinal and angular movement.

I have found that the digging of sandy, loosely packed soil i greatly improved by turning the beveled working face 25 of the bits mounted in the enlarging holders I21), I20, |2d inwardly toward the center of the holder as shown diagrammatically in Fig. 7. Hard, stony soils and clay, on the other hand, are effectively dug by orienting the digger-bits in the enlarging holders in the opposite direction, as shown in Fig, 8, with the beveled working face 25 angled outwardly from the adjacent side of the holder. In the preferred embodiment, the shank of the bit is pentagonal in cross-section, as above described, and

. permits the blade of the bit to be turned through an angle of about 72 to either side of the normal cross-wise blade position. In short, the angularity obtained by using the pentagonal bit permits highly effective working areas and angular relationships to be obtained for different types of soils with but a single bit and holder construc- The invention obviously is not limited to con-. structions in which the enlarging holders are staggered alternately to the right and left, only the preferred embodiment being illustrated. The invention would, therefore, include constructions in which pairs of right and left hand holders are mounted side by side on a common body or saddle portion. The side by side position of such holders tends to balance the lateral twisting forces to which the digger chain is subjected by a single holder and bit. Such twisting forces,

of course, increase as the lateral offset of the" holders .is increased, making the side by side,

mounting particularly advantageous for pairs of holders having large digging span, say of eleven inches or more.

While it might be thought that the present construction of digger-bits and holders would be ineffective to elevate substantial amounts of earth out of thetrench, the contrary is true. The present construction not only loosens the soil with great effectiveness but also carries the loosened material upwardly to the surface of the ground with a high degree of efliciency without resorting to the use of buckets or pockets of any kind. Moreover, the multiple position locking structure of the bits and holders enhances the digging characteristics of the chisel-like blade portions of the bits.

Non-clogging and self-cleaning operation of the chain is provided by vertical escape holes or ports located in the central portion of the saddle 29 of the holders. The flexing of the chain and the pressure of soil or dirt on the chain will force any material entrapped between the chain and the holder upwardly and outwardly through the escape holes 49. For the holders having the clamping portion 31 mounted directly over the saddle, additional transverse passages 5|] are provided in the column-like body of the clamp to complete the escape path of the dirt from the underside of the saddle 29 to the outside of the holder.

I claim as my invention:

1. For use with a trenching machine having an endless loop of digger chain with a series of digger-bit holders mounted thereon, each of said holders having a clamp defining a pentagonal opening with an abrupt shoulder extending into the latter near the trailing end of said clamp and a transverse bolt lying at least partially within said opening, a digger-bit having a shank portion of pentagonal cross section of a size adapted. to be gripped in said clamp, and a blade portion, said blade portion having a transverse cutting edge and a bevelled lower working face extending rearwardly and downwardly from said cutting edge to the opposite side face of said shank portion, said blade portion also having a rearwardly extending upper face of triangular shape to provide side draft for said lower working face. the shank portion of said digger-bit having a plurality of transverse grooves spaced from the rearward end of said digger-bit a distance corre sponding to the distance between the transverse bolt and the shoulder of said holder to locate positively the blade of said digger-bit in a selected one of a plurality of predetermined angular positions relative to said holder. v

2. For use with a trenching machine having an endless loop of roller chain, the chain having pairs of over-lapping inside and outside links, the combination comprising a bit having a blade portion and a polygonal shank portion with trans verse grooves in the ridges thereof, a holder for said bit having a saddle portion and downwardly projecting legs, said legs having spaced holes therein arranged for connecting said holder to the chain in place of a pair of outside links of the latter, said legs having rearwardly extending projections adjacent their upper ends shaped to bear against the upper edge of the next following outside links of the chain, said holder. also having an opening positioned centrally of said saddle, clamping means on said holder for gripping the shank portion of said bit, said clamping means including an upwardly extending column member integral. with. said saddle of. the holder and a pair of gripping jaws in the upper end portion thereof, said jaws defining a polygonal bore corresponding in shape-to that of the shank portion of the bit, said column and jaws being positioned on said saddle to permit free passage of earth through the central opening in the latter,

and a removable tightening bolt positioned transversely of said jaws and lying partially within the bore defined. by the jaws to engage the sides of 10 one of the grooves of said shank portion of the bit.

GLENN W. MCININCH.

& References. Cited in the file of this patent UNITED STATES PATENTS Number Name Date.- Morrow Nov. 1, I892 Traphagen May 4, 1897 Gilman Oct. 4, 1904 Levin Jan. 4, 1910 Hultquist May 27, 1913 Kittredge Mar. 16, 1920 Yocum Oct. 30, 1934 Stenger et a1 Aug. 13, 19470 Rupp V Nov. 2'7,v 1945 

